Flexible staybolt structure



1934 J. KINDERVATER FLEXIBLE STAYBOLT STRUCTURE Filed April 10, 1933'FIG.3

INVENTOR- JD/ms Kfndervafiar- Patented Dec. 18, 1934 UNITED STATESFLEXIBLE STAYBOLT STRUCTURE Julius Kindervater, Richmond, Va.Application April 10,, 1933,, Serial No. 665,251

1 Claim.

This invention relates to a particular type of flexible stayboltstructure, as will later more fully appear, and has for itsprimaryobjectthe devising of an improvement directed to increasing thelife of a feature of the bolt and thereby increasing another type ofbolt. This invention relates tothe last mentioned type of bolt.

A legal requirement is that boiler staybolts be inspected at designatedperiods. This is a costly procedure with all types of bolts, but much,less costly with the type wherein the tell-tale hole extends entirelythrough the bolt from end to end. In this type of bolt all that isnecessary as a preliminary step to making the hydraulic test required isto force' a rodthroughthe tell-tale hole to make sure that it is notobstructed.

In flexible staybolt structures the outer end of the bolt is providedwith ahead, and a sleeve is usually employed for supporting the head. Inthe present type of bolt the tell-tale hole is open at its outer end tothe atmosphere, and a sealing flexible diaphragm or other elementconnects the outer end of the bolt with the sleeve to provide asteam-tight closure to prevent any steam or water that may enter thesleeve from'passing to the ex.-

terior.

While the through tell-tale hole bolt is a superior type from thestandpoint of economy of inspection, it nevertheless can easily be madea non-competitive type because of the cost of. nufacture of the flexibleelement unless such cost can be reduced to a minimum. Therefore, it ishighly desirable, if not absolutely necessary, to employ the simplestand consequently the cheapest type of flexible element, which,obviously, is that of general disc formation. It is comparatively easyto build up the cost of the flexible feature to an amount equal to orgreater than the bolt itself, and no elaborate or complex type offlexible feature, such for instance as that shown in the Budwell Patent1,603,579, is, for this reason, feasible. 1

An essential requirement of this type of staybolt is that it shall havea sufilciently long life to make it commercially practical. In servicethe bolt head and sleeve are subjected to frequent relative movementswhich include relative longitudinal movement as is well known, as wellas universal movements provided for by the flexible jointure. Thesemovements induce a corresponding flexure or distortion of the flexibleelement, and it has been found that the simpler forms of flexibleelements are-of shorterlife than the more elaborate types such thatshown in the Budwell patent.

The problem therefore is to improve the simpler low cost diaphragm ordisc-like structure 'so as to increase its life and thereby make itpractical for use in'the aforesaid typeofstayboIt having a tell-talehole, open at the outer end. This invention is'directed to animprovementpf such flexible diaphragm element of substantial discformation. '2 Referring-to thedrawing: Figure l is a centrallongitudinal sectional view of a staybolt structure embodying thepresent invention, secured to the boiler sheets fragmentally showninsection, the bolt being shown in elevation; Fig. 2 is a fragmental-View, the left half being similar to the upperleithalf of Fig. 1,butshowing the diaphragm-like sealing member inthe process of beingassembled, and the right half-being an elevation; Fig. 3 is a plan viewof the bolt; Fig.

PATENT OFFICE v 4 is a plan View of the cap for the sleeve; and

Fig; 5 is a central sectional'elevation of. thependingapplicationSerialNo. 572,564, filed No vember '2, 1931, issued as PatentNo. 1,909,108, May 16, 1933 and attention is invited to this co-'pending application" for a more complete detailed description ofvariousof the parts; The present inventionhowever is in no way' restrictedtoany particular design, but is applicable to any design of this type ofstaybolt structure. f

Referring more particularly to the several views, an open ended sleeve 1is supported in an orifice in ari'outer sheet 2 of aboil'er, to which itis secured, by welding, all in the usual manner. A bolt 3 having itsinner end threaded, extends through the sleeve, projecting from theouteropen end and extending from the inner open end, through the boiler, andis screwed into a threaded opening in an inner sheet 4 of the boiler,and

headed over at the inner end, all in the usual manner. A head 5,provided-with slots -6- for engagement by a tool to facilitate theassemblage of the bolt'in the usual manner, isformed at the outer endportion of the bolt, and is provided with a face 7 supported upon a seat8 provided within the sleeve, a flexible connection between the bolt andsleeve being thereby provided;-

A tell-tale hole 9" extends throughout the entire length of the bolt.The upper end of the sleeve provides a transverse seat 10 for thesealing dia phragm, which is indicated generall'y'bythereference Theouter end of the bolt is threaded and-contractedto formanother-transverse seat 1 1 for the diaphragm A. A cap 12 having acentral orifice to permit the bolt to extend therethrough, is screwed onto the sleeve against the diaphragm to hold the diaphragm in steam-tightengagement upon the seat 10. A backing 13 is mounted on the end of thebolt suitably spaced from the cap to permit the required relativemovements, and is held tightly against the diaphragm by a nut 14,screwed on the end of the bolt, to make a steamtight joint between thebolt seat 11 and diaphragm. Obviously, if desired, the backing and nutmay be formed as one piece.

The diaphragm is made of flexible non-rustable sheet metal, and in theusual former practice, it

. is given a permanent shape more or less similar to that shown inFig. 1. As this bolt in service moves relative to the sleeve, thepermanently formed corrugation of the diaphragm is compelled to flex atthe permanent bend or bends forming the corrugationyand it has beenobserved that the diaphragm often first breaks down-at a bend. It iswell known that a peris shaped during its manufacture substantially asshown in Figs. 2 and5.

The diaphragm A has a central perforation or opening 15 through whichthe outer threaded end of the bolt passes, and further comprises in itspresent preferred form, an outer horizontal sealing margin 16 havinginner and outer peripheral edges 16a and 161), respectively; an innerhorizontal margin 17, spaced above the outer margin and having an innerperipheral edge 1711 around the perforation 15 and an outer peripheraledge 17b; and a connecting wall 18 having an outer peripheral edge 18adirectly and integrally connected to the inner edge 16a of the outermargin and an inner peripheral edge 18b directly and integrallyconnected to the outer edge 17b of the inner margin. The wall ispreferably formed, as shown, somewhat converging upwardly.

The inner margin 1'7 comprises, around its inner edge 17a, a sealingportion 170 which is confined between the seat 11 and backing 13, andaround its outer edge 172) a spring portion 17d. This spring portion 17dand the wall 18 span the space which is provided in the bolt assemblagebetween the seats and 11.

In assembling the parts of the staybolt structure the sleeve and boltare assembled with and connected to the boilersheet, as shown in Fig. 1.The diaphragm is then mounted on the outer end of the bolt and itsmargin 16 is disposed on the seat 10 of the sleeve. The cap is thenscrewed into'place to make a steam-tight joint, as shown in Fig. 2. Thebacking 13 is mounted on the end of the bolt in engagement with thesealing portion 170 of the inner margin 17 of the diaphragm, and the nut14 is screwed down upon the outer end of the bolt. The backing 13 isthereby gradually forced inwardly and the sealing portion 170 of thediaphragm is likewise gradually forced inwardly closer to the plane oftheouter margin 16 until, in the preferred embodiment as shown, it isfinally forced to its adjusted position upon its seat 11 in the sameplane with the outer margin 16 where it forms a steam-tight joint.

During this adjustment the spring portion 17d of the diaphragm margin 17is constrained to place it under spring tension. During this adjustmentthis spring portion gradually assumes a natural temporary bend to springenergize it, and when in its final adjusted position it forms with thewall 18 a corrugation-like circular bulge, substantially as shown inFig. 1.

It will be apparent that when the bolt moves relative to the sleeveunder service conditions, the diaphragm will be correspondingly flexedto compensate for such movements, but will not act in the manner of theusual diaphragm of the permanent corrugation construction that haspreviously been referred to. With the diaphragm of the present inventionthere will be what will more nearly approximate a purely spring actionor movement with a minimum of cracking stress at the angles. In short,the tensioned spring portion of the daiphragm of the present inventionwill alternately be slightly deenergizedand reenergized during itsdifferent alternate movements from and to its normal position.

The improvement of the diaphragm as above set forth has been found toincrease its life of service materially without increasing its cost ofproduction, and has thus placed this type of stay-- bolt on acompetitive equality with the present commonly employed flexiblestaybolt having the tell-tale hole closed at the outer end and whichemploys a closed cap for the sleeve instead of a diaphragm.

While there has been hereinbefore described a preferred embodiment ofthe present invention, it will be understood that many and variouschanges and modifications in form, structure and design may be madewithout departing from the spirit of the invention and that all suchchanges and modifications are contemplated as a part of the presentinvention as defined in the appended claim.

The invention claimed and desired to be secured by Letters Patent is:

A boiler staybolt assemblage comprising a sleeve having a seat; a bolthaving a head normally engaging said seat in flexible connectiontherewith; and a perforated resilient sealing dia phragm comprising anouter margin having an outer peripheral edge connected with said sleevebeyond said seat and an inner peripheral edge, an inner margin having aninner peripheral edge around the perforation secured to said head beyond the part thereof normally engaging said seat and an outerperipheral edge, said inner margin around its outer edge constituting aresilient flexible portion, flexed when said head is engaged with saidseat to substantially frusto-conical ring shape energizing saiddiaphragm, said por tion being deenergized and of relatively flat ringshape when unflexed, and a ring-shaped wall having an edge connectedwith the inner edge of said outer margin and extending angularlytherefrom and having its opposite edge connected with the outer edge ofsaid inner margin, said wall and flexible portion constituting acorrugation-like circular bulge when said flexible portion is flexed.

JULIUS KINDERVATER.

